PROJECT PROFILE ® Teretek Stabilises N19AR122 Structural Footings Supporting Murray Irrigation Canal Regulators

INDUSTRY Summary Infrastructure Murray Irrigation delivers water, sourced from the , to over 2,000 properties STRUCTURE Canal regulators across the NSW region. The Canal forms the backbone of the Murray Irrigation delivery system, controlling the flow of local river and creek systems. The PROBLEM is 2,880 kilometres long and is the largest private irrigation canal in the Ground settlement southern hemisphere, spreading across the southern Riverina plain to and LOCATION suppling water to 700,000 hectares. Blighty, NSW Numerous gates along the Mulwala Canal (known as regulators) maintain the water DURATION / YEAR depth and control water flow along the channel. The regulator gates are supported by 26 days (June-July 2019) reinforced concrete footings, designed to support the regulator structures and their TECHNOLOGY applied loads, the roadways that pass on top and direct the canal water through the ® Teretek regulators. BUSINESS UNIT Mainmark Australia During a program of maintenance works, 65 regulators were scheduled to be upgraded, with plans to custom-fit concrete upstream sections onto existing structures and establish sill heights for new regulator gates. Visual inspections of three existing regulators, Sprys, Mundiwa and Mulwala 20, Above: Aerial view of site showing Mainmark revealed significant cracking and evidence of ground settlement and wash-out affecting crew treating ground the foundations of the structures. Work had been undertaken at these sites some years settlement under earlier to facilitate the installation of lay-flat gates, at which time there was no indication regulator gates. of any structural issues or voids. Further investigation using drills and probes, revealed a number of structural problems including extensive voids, washout of the subgrade, as well as the saturation and weakness of the residual materials beneath the footings supporting the three regulators. PROJECT PROFILE N19AR122

Teretek® Stabilises Structural Footings Supporting Murray Irrigation Canal Regulators continued

Above: Panoramic view of job site.

The concrete foundation slabs had also subsequently Solution cracked and exhibited signs of settlement, impacting Mainmark’s proprietary Teretek® engineered resin the floor and apron of the regulator at each site. injection provided a cost effective and efficient The Sprys site was the worst affected, with a void remediation solution that was perfectly suited to the measuring approximately 23m3. project’s site conditions. Being extremely durable and To prevent destabilisation of the regulator’s structural environmentally inert, Teretek was also considered a footings and the road bridges running across the top safe solution that would have no determinantal impact of them, Murray Irrigation Limited (MIL) approached on the canal. Mainmark to deliver an efficient and cost-effective Teretek is a unique two-in-one solution that increases remediation solution that was suitable for the canal both ground bearing capacity and fills voids. conditions and capable of improving the ground Technicians apply the solution via a number of very bearing capacity beneath the regulators. small injection points under the impacted structure in a process similar to keyhole surgery; injecting the expanding polyurethane resin mix through 16mm Objectives tubes into the ground beneath the footings. On entering the ground, the resin rapidly expands, filling The primary objective was to mitigate severe any voids encountered, compacting weak soils and subsidence affecting the regulator foundations, filling adding volume to the ground, thereby increasing its extensive voids and compacting the weak soil to bearing capacity. improve bearing capacity of the substrate surrounding the footings. The solution needed to rectify the structural issues and overcome the need to replace the affected regulators. Only when the 500km channel was drained of water was it possible to determine the full scope of works, which was more extensive than forecasted, encompassing a total of 15 different sites. Due to the location, project timelines were strictly limited to a short window when the canal would be completely drained of water. Mainmark worked closely with MIL to adapt the solution to complete the full scope of works, treating 15 sites, before the channel was refilled for spring irrigation. Above: Mainmark technician monitors the readings from a laser level while injecting Teretek. www.mainmark.com PROJECT PROFILE N19AR122

Teretek® Stabilises Structural Footings Supporting Murray Irrigation Canal Regulators continued

Teretek also assists in reducing water movement below the impacted slabs, mitigating the risk of water leakage or further washout of subgrade materials. The solution helps to mitigate soil subsidence and further structural deterioration including cracking and movement. The Teretek injection points at each site were laid out in an approximately 1.2m centre to centre grid allowing the resin solution to be injected under the affected slabs, including under the reinforced mass concrete flooring beneath the lay-flat gates. The slabs ranged in thickness from 250mm at the outlet apron slab, to 1000mm thick at the inlet slab under the lay- flat gates.

Three self-contained Mainmark Rigs were used to Above: Discussions with the client on the road-way while work access the 15 sites which spanned a distance of continues below. Collaboration between Mainmark and Murray 250km. The Rigs were used to transport all required Irrigation was a key element to the project’s success. Mainmark technicians, equipment and materials necessary to deliver the project to each site. Additional This complex project was completed over a period Mainmark personnel were on standby to cover shifts of 26 days using a total of 14.5 tonnes of Teretek allowing the agreed project timeline to be met. across the three regulator sites. The project delivered a successful outcome that avoided the need to replace the regulators, and the mobile access platform constructed for the project will be a useful asset for future MIL works. Murray Irrigation Limited Project Manager, Matthew Close, spoke of the success of the works: “Mainmark’s void filling program for our undermined bridge regulators was thoroughly successful. The works were completed well within the limited time constraints and under budget. The crew was also a pleasure to have onsite with all challenges met with optimism. We look forward to the opportunity to work with Mainmark again in the near future.” Above: Drilling to access voided area.

To help ensure strict safety protocols were adhered to throughout project delivery, a bespoke mobile access platform with stairs was constructed to allow technicians to access the sites safely and efficiently. Close collaboration between MIL and Mainmark was required throughout the project to ensure technicians were mobilised quickly and efficiently. www.mainmark.com